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Security Advisory CERT-NL
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Author/Source : Jan Meijer Index : S-99-09
Distribution : World Page : 1
Classification: External Version: 1
Subject : S-99-09 : CERT Summary Date : 26-Feb-99
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By courtesy of CERT Coordination Center we received the following
information.
CERT Coordination Center advisory CA-99.01:CERT Summary reports the
following trends in incidents since the last CERT summary, issued in
December 1998 (CS-98.08):
1. Widespread Scans
2. Back Orifice and NetBus
3. Trojan Horse Programs
4. FTP Buffer Overflows
CERT-NL recommends to be extra cautious for these specific types of
incidents.
This advisory is meant to provide you with information about the current
trends. Where normally we would only forward you the URL, we thought
this information to be of such interest to include the full text here.
All CERT Coordination Center advisories and README's are mirrored by
CERT-NL.
The specific URL for this case is:
ftp://ftp.nic.surfnet.nl/surfnet/net-security/cert-cc-mirror/cert_summaries/CS-99.01
More information about the CERT-NL mirror and notifier services is
contained in News items N-95-01 (notifier) and N-95-02 (CERT mirror),
both present on ftp://ftp.surfnet.nl/surfnet/net-security/cert-nl/docs/news/
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CERT Summary CS-99-01
February 23, 1999
The CERT Coordination Center periodically issues the CERT summary to
draw attention to the types of attacks currently being reported to our
incident response team, as well as to other noteworthy incident and
vulnerability information. The summary includes pointers to sources of
information for dealing with the problems.
Past CERT summaries are available from
http://www.cert.org/summaries/
______________________________________________________________________
Recent Activity
Since the last CERT summary, issued in December 1998 (CS-98.08), we
have seen these trends in incidents reported to us.
1. Widespread Scans
We continue to receive numerous daily reports of intruders using
tools to scan networks for multiple vulnerabilities. Intruder
scanning tools continue to become more sophisticated.
On January 28, 1999, we published an incident note describing a
new scanning tool that searches for multiple known vulnerabilities
on remote systems. The tool incorporates probes for known
vulnerabilities, remote operating system identification, and a
scripting language that simplifies automation of probes and
exploitation attempts. For more information, see our incident note
at
http://www.cert.org/incident_notes/IN-99-01.html
Reports also indicate that scanning techniques addressed in
previous CERT incident notes, such as scripted tools and stealth
scanning, are still being employed by intruders. For more
information, see
+ http://www.cert.org/incident_notes/IN-98-06.html
+ http://www.cert.org/incident_notes/IN-98-05.html
+ http://www.cert.org/incident_notes/IN-98.04.html
+ http://www.cert.org/incident_notes/IN-98.02.html
The daily reports of widespread scans and exploitation attempts
involve many vulnerabilities; however, the most frequent reports
involve activity with well-known vulnerabilities in "mountd",
"imap", and "pop3" services for which CERT advisories have been
published. These services are installed and enabled by default in
some operating systems. The scans and exploitation attempts still
result in sites being compromised. See the following advisories
for more information:
+ sunrpc (tcp port 111) and mountd (635)
http://www.cert.org/advisories/CA-98.12.mountd.html
+ imap (tcp port 143)
http://www.cert.org/advisories/CA-98.09.imapd.html
+ pop3 (tcp port 110)
http://www.cert.org/advisories/CA-98.08.qpopper_vul.html
We encourage you to make sure that all systems at your site are up
to date with patches and that your machines are properly secured.
2. Back Orifice and NetBus
We continue to receive daily reports of incidents involving
Windows-based "remote administration" programs such as Back Orifice and
NetBus. Occasionally these are reports of compromised machines that
have one of these tools installed. However, the majority of these
reports involve sites that have detected intruders scanning for the
presence of these tools. These scans may appear as unauthorized traffic
as follows:
+ NetBus - connection requests (SYN) packets to TCP ports
12345, 12346, or 20034
+ Back Orifice - UDP packets to port 31337
Keep in mind that these tools can be configured to listen on
different ports. Because of this, we encourage you to investigate
any unexplained network traffic.
For more information about Back Orifice, review CERT vulnerability
note VN-98.07:
http://www.cert.org/vul_notes/VN-98.07.backorifice.html
3. Trojan Horse Programs
Over the past few months, we have seen an increase in the number
of incident reports related to Trojan horse programs affecting
both Windows and UNIX platforms.
+ CERT advisory CA-99-02 includes descriptions of several
recent incidents involving Trojan horse programs, including a
false upgrade to Internet Explorer, a Trojan horse version of
TCP Wrappers, and a Trojan horse version of util-linux. The
advisory also provides advice for system and network
administrators, end users, software developers, and
distributors. The advisory is available from
http://www.cert.org/advisories/CA-99-02-Trojan-Horses.html
+ CERT advisory CA-99-01, discusses the Trojan horse version of
TCP Wrappers in greater detail, and provides information on
how to verify the integrity of your TCP Wrappers
distribution.
http://www.cert.org/advisories/CA-99-01-Trojan-TCP-Wrappers.html
4. FTP Buffer Overflows
Very recently, we have received a few reports of intruders
scanning for and exploiting a remote buffer overflow vulnerability
in various FTP servers. By supplying carefully designed commands
to the FTP server, intruders can force the server to execute
arbitrary commands with root privilege. Intruders can exploit the
vulnerability remotely to gain administrative access. We encourage
you to review text provided by Netect, Inc. in CERT advisory
CA-99-03, which describes the ftpd vulnerability in more detail.
The advisory is available from
http://www.cert.org/advisories/CA-99-03-FTP-Buffer-Overflows.html
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CERT-NL is the Computer Emergency Response Team for SURFnet customers. SURFnet
is the Dutch network for educational, research and related institutes. CERT-NL
is a member of the Forum of Incident Response and Security Teams (FIRST).
All CERT-NL material is available under:
http://www.surfnet.nl/surfnet/security/cert-nl.html
ftp://ftp.surfnet.nl/surfnet/net-security
In case of computer or network security problems please contact your
local CERT/security-team or CERT-NL (if your institute is NOT a SURFnet
customer please address the appropriate (local) CERT/security-team).
CERT-NL is one/two hour(s) ahead of UTC (GMT) in winter/summer,
i.e. UTC+0100 in winter and UTC+0200 in summer (DST).
Email: cert-nl@surfnet.nl ATTENDED REGULARLY ALL DAYS
Phone: +31 302 305 305 BUSINESS HOURS ONLY
Fax: +31 302 305 329 BUSINESS HOURS ONLY
Snailmail: SURFnet bv
Attn. CERT-NL
P.O. Box 19035
NL - 3501 DA UTRECHT
The Netherlands
NOODGEVALLEN: 06 52 87 92 82 ALTIJD BEREIKBAAR
EMERGENCIES : +31 6 52 87 92 82 ATTENDED AT ALL TIMES
CERT-NL'S EMERGENCY PHONENUMBER IS ONLY TO BE USED IN CASE OF EMERGENCIES:
THE SURFNET HELPDESK OPERATING THE EMERGENCY NUMBER HAS A *FIXED*
PROCEDURE FOR DEALING WITH YOUR ALERT AND WILL IN REGULAR CASES RELAY IT
TO CERT-NL IN AN APPROPRIATE MANNER. CERT-NL WILL THEN CONTACT YOU.
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